Cementless Distal Fixation Modular Stem Hemiarthroplasty without Calcar Replacement in Geriatric Unstable Intertrochanteric Femur Fractures

Background This study evaluated the outcomes of hemiarthroplasty using a cementless, distally fixed modular femoral stem without calcar reconstruction in geriatric unstable intertrochanteric femur fractures and investigated factors influencing postoperative femoral stem subsidence. Methods A total of 48 patients who underwent hemiarthroplasty with a cementless distally fixed modular femoral stem for unstable intertrochanteric fractures were retrospectively reviewed. Clinical outcomes were assessed using the Cumulative Ambulation Score (CAS), Harris Hip Score (HHS), and Visual Analog Scale (VAS). Radiographic evaluation included femoral stem subsidence, canal fill ratio (CFR), radiolucent lines suggestive of osteolysis at the distal fixation zone, and new bone formation around the stem. At final follow-up, patients were divided into two groups according to stem subsidence (≤3 mm vs >3 mm), and clinical and radiographic outcomes were compared. Statistical significance was set at p<0.05. Results The mean age was 82.7 years, and the median follow-up was 32 months. Sixteen patients (33.3%) had no stem subsidence. Subsidence was observed in 32 patients (66.7%), with a median magnitude of 4.2 mm (range, 1.1–17.3 mm). Seventeen patients had subsidence >3 mm, whereas 15 had subsidence ≤3 mm. The mean early postoperative endosteal CFR was significantly lower in the >3 mm group (0.74; 74%) than in the ≤3 mm group (0.89; 89%). HHS showed no statistically significant difference between preoperative and postoperative measurements; however, patients with subsidence >3 mm demonstrated a significant decrease in CAS. Conclusions This study demonstrated that hemiarthroplasty performed using a cementless distally fixation modular femoral stem yields satisfactory outcomes in geriatric unstable intertrochanteric femur fractures. In the post-operative period, endosteal CFR was the main determinant of femoral stem subsidence and clinical success. To achieve a successful outcome, surgeons should aim to obtain a CFR of approximately 0.90. Because CFR is an important determinant of adequate mechanical stability and osseointegration. Trial registration Clinical trial number: not applicable